Sensitizing dyes from 2-methyl-4, 5-dihydro-beta-naphthothiazole



United Sttes Patent C-C SENSITIZING DYES FRGM 2-METHYL-4,5-DI- HYDRO-BETA-NAPHTHOTHIAZOLE George de Stevens, Portland, Conn., assignor to Sperry Rand Corporation, a corporation of Delaware No Drawing; Application May 10, 1955 Serial No. 507,459

16 Claims. (Cl. 260-440) My invention relates to the production of sensitizing dyes from a new heterocyclic base which I have desig nated as 2-methyl-4,S-dihydro-B-naphthothiazole.

Cyanine dyes contain at least two auxochromic nitrogen atoms, the one ternary and the other quaternary, the one nitrogen atom lying in one heterocyclic nucleus and the other lying in another heterocyclic nucleus, the two nitrogen atoms being connected by a conjugated carbon chain.

I have now found that it is possible to prepare cyanine dyes in which one or both of the above mentioned auxochromic nitrogen atoms lie in a 4,5-dihydro-p-naphthothiazole nucleus. I have further found'that these new cyanine dyes sensitize photographic emulsions strongly and cleanly, i.e. without producing excessive fog or residual dye stain.

It is accordingly an object of my invention to provide new cyanine dyes. A further object is to provide photographic emulsions sensitized with such dyes. Other objects will appear hereinafter. I

As starting material for the preparationofmy new dyes I employ 2-alkyl-4,5-dihydro-fimaphthothiazoles, particularly 2-methyl-4,5-dihydro-/3-naphthothiazole. I first convert these alkyl-4,S-dihydro-fi-naphthothiazole 2,905,666 Paieaied sepi; 22 159 2.. triethyl amine, trimethalamine and N-methyl piperidine). I have found it advantageous to employ a mixture of pyridine with a strong tertiary organicbase.

Instead of 2-halogenoquino1inequaternary salts I can employ 2-alkyl mercapto or 2-aryl mercapto quinoline quaternary salts to condense with the quaternary salts of 2-alkyl-4,5-dihydro-p-naphthothiazole, in the presence of an'acid binding agent." V

Using 2-halog'ehopyridine quaternary salts'insteadof z halogenoquinoline; quaternary salts I can prepare pyridocyanine dyes containing a 4,5-dihydrofl-naphthothiazole nucleus; I

UsingQZ-alkyl mercapto or 2-a ryl mercaptob'en'zothiazole or. naphthothia'zole salts I ca'n prepare simple cyanine dyes other than'pseudocya'nine dyes. H

' To prepare symmetrical carbocyanine dyes from-{2 alkyl-4,5-dihydro-B-naphthothiazole quaternary salts, I react the. quaternary" salts with esters ofortho acids, e.g. ethylorthoformate, ethylorthoacetate, ethyl orthopropim nate and iethyl or' thobenzoate' in the presence of pyridine or a mixture of pyridine and triethylamine.

To prepare unsymmetrical earbocyanine. dyes; fl'QlII 2- alk'yl-4,5 dihydrorfirnaphthothiazole quaternary salts I re act the quaternary salts with cycloammonium quaternary salts containing a B-aryl aminovinyl group in the alpha or gamma position, i.e. IILODB of the so-called reactive positions in the presence of an acidebinding agent, e.g. pyridine or pyridine plus triethyl amine.

To prepare styryl dyes from my new quaternary salts I condense them with p-dialkyl aminobenzaldehyde in the presence of an alkaline catalyst, erg. piperidine in absolute ethanol solution.

bases to quaternary salts by reacting the base with esters,

such as alkyl halides, alkyl sulfates, or alkyl-p-toluene sulfonates, for example. For purposes of convenience the quaternary salts useful in practicing this invention can be represented by the following single formula:

it X- wherein- R represents an alkyl group, eg methyl, ethyl, n-propyl, isobutyl, n-butyl, ii-hydroxyethyl, fi-methoxyethyl, a-ethoxyethyl, fi-ac'et'oxyethyl, p-carboxyethyl, carboxymethyl, 13 carbomethoxyethyl, ,B carbethoxyethyl, allyl, etc. or an aralkyl group, e.g. benzyl, phenyl, ethyl, etc., R represents methyl, ethyl or n-propyl and X- represents an anion, e.g. chloride, bromide, iodide, benzene sulfonate, p-toluene sulfonate, methyl sulfate, ethyl sulfate, thiocyanate perchlorate, acetate, etc.

To prepare pseudocyanine dyes from such quaternary salts I react thequaternary salts with u-halogenoquinoline quaternary salts, inthe presence of an acid binding agent, such for -gexample as sodium ethylate; sodium carbonate, pyridine or a strong organic base (e.g.

To prepare merocarbocyanine dyes from 2-alkyl-4,5- dihydrdp-naphthothiazole quaternary salts I condense the quaternary salts with'ketomethylene heterocyclic intermediates containingwan aryl amino-methylene group in -p s an. n hence a a db n ng a e e.g.'; pyridine plus triethyl amine; Examplesofsuch keto: methylene intermediates are: S-acetanilido methylene3 ethylrhodanine, 5-acetanilidornethylene-3-ethyl-l-phenyh patented December 14, 1943.

It is well known that cyanine dyes resonate between two extreme forms and that a cyanine dye can be represented by either of the two extreme forms. Thus, the unsymmetrical type of instant dyes can be represcnted by either of the following formulas.' I

' Example I.2-methyl-4,5-dihydro-fl-naphthothiazole at s CH OCHs 110 g. (1 mol) of 2-bromo-tetralone (Wilds, J.A.C.S. .68, 86 (1946)), 36.5 g. (1 mol) of thioacetamide and .175 ml. of absolute ethyl alcohol wereheated slowly on the steam bath under reflux. Within a short time a vigorous reaction ensued and a copious white solid precipitated. After the reaction subsided, the mixture .was refluxed on the steam bath for 3 hours. The alcohol was then distilled off and the chilled residue was made alkaline with NH OH and this solution was thoroughly extracted with ether. The ether extract was dried over K CO The ether was then removed by distillation and the residue was .distilled at reduced pressure. 2-methyl-4,5-dihydro-finaphthothiazole was collected in 41% yield at 136-137 at 1.5 mm. pressure.

' Example 2.-2-methyl-4,5-dihydr0-fi-naphthothiazole metho-p-toluene sulfonate 17 g. (1 mol) of 2-methyl-4,S-dihydro-fl-naphthothiazole and 16.8 g. (1 mol plus excess) of methyl-ptoluene sulfonate were heated in an oil bath at 120 for 1 hour and then on the steam bath for 4 hours. The resulting solid cake was washed well with ether, then acetone and dried in vacuo. Yield: 23 g. 72% of theoretical. M.P. 155.

. Example 3.--2-methyl-4,5-dihydro-fi-naphthothiazole ethiodide Example 4.3,3'-dimethyl-4,5,4',5'-dibenz0-6,7,6',7'-

tetrahydrothiacarbocyanine iodide 5 g. (1 mol) of Z-rnethyl-4,5-dihydro-fl-naphthothiazole methyl-p-toluene sulfonate, 5.7 g. (1 mol plus 200% excess) of ethyl orthoformate and 20 ml. of pyridine were refluxed for 3 /2 hours. After chilling the reaction mixture overnight, the precipitate was collected on a filter, washed well with water, then acetone and air dried. The crude dye was dissolved in ml. of boiling methyl alcohol and to this was added 2 g. of NaI dissolved in 20 ml. of methyl alcohol. A precipitate was immediately obtained. An additional 200 ml. of methyl alcohol was added to the boiling mixture to bring the dye completely into solution. On cooling, green needles were obtained which were collected on a filter and washed with methyl alcohol. Yield of crude dye: 0.5 g. 14%. It was purified by recrystallizing twice from methyl alcohol (300 ml. per gram). The yield of olive green velvet-like needles was 8%, M.P. 244245. A solution of the dye in methyl alcohol was blue with an absorption maximum at 586 mu.

Example 5.3,3-diethyl-4,5,4',5',-dibenz0-6,7,6,7,- tetrahydrothiacarbocyanine iodide I C311 C2 5 5 g. (1 mol) of 2-methyl-4,5-dihydro-B-naphthothiazole ethiodide, 5.7 g. (1 mol plus 200% excess) of ethyl orthoformate and 25 ml. of pyridine were refluxed for 3 /2 hours. After chilling the reaction mixture overnight, green needles were precipitated which were collected on a filter, washed well with water, then acetone and air dried. In this manner, 1.6 g. (38%) of crude dye was obtained. The dye was recrystallized twice from methyl alcohol to give a 29% yield of green needles with a golden reflex, melting at 244 d. A solution of the dye in methyl alcohol was blue with an absorption maximum at 586 mu.

Example 6.-3,3'-diethyl-4',5'-benz0-6',7'-dihydr0 oxathiocarbocyanine iodide 1.8 g. (1 mol) of 2-methyl-4,5-dihydro-,8-naphthothiazole ethiodide and 2.4 g. (1 mol) of 2-fl-acetanilidovinyl benzoxazole ethiodide were dissolved in 15 ml. of boiling absolute ethyl alcohol. To this solution was added 1 g. (2 mol) of triethylamine and the whole was refluxed for 15 minutes. After chilling overnight, the dye crystals were collected on a filter, washed well with water, then acetone, and dried in vacuo. The yield of crude dye was 70%. After two recrystallizations from methyl alcohol (100 ml. per gram) 1.2 g. (46%) of pure dye in the form of fine dark green needles, M.P. 224 d., was obtained. A solution of the dye in methyl alcohol was red with an absorption maximum at 530 mu.

Example 7.1'-ethyl-3-methyl-4,5-benzo-6,7-dihydrathia-2'-cyanine iodide /CH2 S (ilHz i ii C-CH Cam 1 1- OH;

1.9 g.'(1 mol) of 2-methyl-4,5-dihydro-B-naphthothia zolelmethyl-p-toluene sulfonate and 2.0 g. (1 mol) iodoquinolineethiodide were dissolved 15 of boiling amosjoeo absolute ethyl alcohol. Tothis solution was added 1 g,

(1 mol) of triethylamine andrefluxing was continued Example-8=-2-p-dimethyl ami'nostyryl-4,5-dihydro-pnaphthothiazole methiodide fi s cm 3.9 g. (1 mol) of 2-methyl-4,5-dihydro-fi-naphthothiazole methyl-p-toluene sulfonate and 1.5g. of p-dimethylaminobenzaldehyde were dissolved in 25 ml. of absolute ethyl alcohol. A drop of piperidine was added to this solution and refluxing was continued for 40 minutes. g. of Nal dissolved in 10 ml. of ethyl alcohol was added to the reaction mixture which was refluxed for an additional 5 minutes. After chilling. overnight, the precipitate was collected on a filter, washed well with water, then acetone and airdried; In this manner, 1.0 g. (21%) of crude dye was, obtained. The dye was recrystallized twice from methyl alcohol (250 ml. per gram) and a 5% yield of pure dye was otbained in the form of red needles .with a-blue reflex, M.P. 215-216". A- methyl alcohol solutionof the .dye-had an absorption maximum at 496 mu.

Example 9.1;,3' diethyl-3,3=dimethyl-4,5-benzo-d'j dihydropseudoindolothia-oarbocyqnine iodide Example 10.'3-efhyl-5-(1 -methy l-4 5-dihydro-j3-n aphthothiazolylz'dene.) ethylidene rhodqnine 1.9 g. (1 mol) of 2-methyl-4,5-dihydro-p-naphthothia. zole methyo -p-toluene sulfonate, 1.5 g. (1 mol) of: 5-

acetanilidomathylene-3-ethyl rhodanine, 15, ml. of abso-. lute, ethyl alcohol and 1 g. (2 mol) of triethylamine were. After chilling overnight, the.

refluxed forylS minutes. dye'crystals' were collected "on a filter, washed well with water, then acetoneand ahjdriedg; "lfhe yield of'orude dye was 84%." The dye was purified'by dissolving it in boilingopyridine and precipitating by the addition of methyl; alcohol. The pure dye was obtained in the form of felted dark red needles with greenish reflex in a 68% yield," melting at 291"with decomposition. A methyl alcohol solutionof the dye had an absorption maximum at 554 mu.

xa ple 1 +3.3?-d e L-9-m y Z +dil1yd Q- Z5- bnzothiacarbocyanineiodide 2.1 g. (1 mol) of 2-(2-methyl mercapto} propenyl) benzothiazole ethyl-p-toluene sulfonate and 1.8' g. (1 mol') of, ,1 2.-n etl 1yl 4.5v dihydro pnaphthothiazole ethiodide were-dissolved in ,15 ,ml;. ofboiling absolute ethyl alcohol; To this solution was thenyadded 10.5 g. (2 mol) of tris hylamineant reflsain awas .q nt nued for 5 min Atfterchilling overn ight, the precipitate was collected on a filter, washedwel-l with water, then acetone and dried in vacuo., In is manner, 1 .1 g. (40%) of crude dye was; obtained... After two recrystallizations, frommethyl alcoho L -:Pr r ,Q%. l of pu e dye was obtained in; e form of fine greenneedles with, golden reflex, MR. 259.? d. A solution of the d316, in methyl alcohol..isaeddish-purpleand h an absorption maximum-at 5 1.3 Exampl'e 12. -[1 ethyl-2(4;5=- dihydro 3 naphtha thiaz0l'e)=] [I phenyl'"-2;5 dimethyl 3-pyrr0le1 dimethine 'cyanine 'io'a'ide v GEE...

1.0 g, (1 mol) of 1-phenyl-2,5-dimethyl-3 pyrrole-aldehyde, 1.75 g. (1 mol) of 2-methy1-5;6-dihydro-fi-naphthothiazol'e ethiodide, 15 cc. of absoluteethyl alcohol and 3 dreps-rofslpiperidinewere: refluxed for -minutes. After chilling overnight, the pre cipitate wascollected on a filter, washed well with water, then acetone and air dried. The yield of pure dye obtained of bright yellow crystals, 'M.P. 226227 duwas, 13% of theoretical. A'methanolsolution, of -the dye gave/,a yellow color with an absorption maximum at 456*- mu.

In the foregoing, I have described-my invention so that it may be practised by those skilled in the art, and I have particularly pointed out the features of novelty, which Iibelie'veto'be characteristic; of m y invention in. the=fo1lowing claims; It will be understood, however, that modificationsandchanges may be made without departing from the spirit I cl substance of my invention, as will-be clear to those; skilled in the art.

l. A dye selected from ,the' group characterized by the'followinggeneralformula; Q I I 'O'H, Q

li I R. R

in which R and R respectively, represent a member selected from the group consisting ofi--alkyl and aralkyl groups and X- represents an acid radical.

in whichR and R respectively represent a member selected from the group consisting of alkyl and aralkyl groups, L represents a methine group, m represents a positive integer from 1 to 2, n represents a positive integer from 1 to 3, both inclusive, X represents an acid radical and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, said heterocyclic nucleus being-selected from the group consisting of a nucleus ofthe oxazole series, a nucleus of the thiazole series, a nucleus of the thiazoline series, a nucleus of the benzoxazole series, a nucleus of the benzothiazole series, a nucleus of the alpha naphthoxazole series, a nucleus of the beta naphthoxazole series, a nucleus of the alpha naphthothiazole series, a nucleus of the beta naphthathiazole series, a nucleus of the selenazole series, a nucleus of the pyridine series, and a nucleus of the 3,3- dialkyl indolenine series.

5. 3,3 diethyl 4,5'-benzo-6',7-dihydrooxathiacarbocyanine iodide having the following structure:

\ o C-CH=CHCH=C (lg 2 2 6. A dye selected from the group characterized by the following general formula:

0 Hz i 8 8. A dye selected from the group characterized by the following general formula: a

, CHI

where R and R respectively represent a member selected from the group consisting of alkyl and aralkyl groups, L represents a-methine group, n represents a positive integer from 1 to 2 and X- represents an acid radical.

9. 2 p dimethylaminostyryl-4,S-dihydro-B-naphthothiazole methiodide having the structure:

| F CHa' :10. A' dye selected from the group characterized by the following general formula:

(12 s V .R

where R represents a member selected from the group v 12. A process for preparing symmetrical carbocyanine dyes havingthe general formula wherein R and R respectively represent members of the group consisting of alkyl and aralkyl radicals and X'- represents an acid radical from a quaternary salt having the general formula wherein R and X- have their previous significance comprising condensing the quaternary salt With an ester of an orthocarboxylic acid in an alkaline medium containing at least one constituent selected from the group consisting of pyridine and a mixture of pyridine and triethylamine.

13. A process for preparing unsymmetrical cyanine dyes having the general formula wherein R and R respectively represent a member selected from the group consisting of alkyl and aralkyl groups, L represents a methine group, In represents a positive integer from 1 to 2, n represents a positive integer from 1 to 3, X- represents an acid radical and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, said heterocyclic nucleus being selected from the group consisting of a nucleus of the oxazole series, a nucleus of the thiazole series, a nucleus of the thiazoline series, a nucleus of the benzoxazole series, a nucleus of the benzothiazole series, a nucleus of the alpha naphthoxazole series, a nucleus of the beta naphthoxazole series, a nucleus of the alpha naphthothiazole series, a nucleus of the beta naphthothiazole series, a nucleus f the selenazole series, a nucleus of the pyridine series, and a nucleus of the 3,3-dialkyl indolenine series from the quaternary salt having the general formula ll C--C H:

wherein R represents a member selected from the group consisting of alkyl and aralkyl groups and X'- represents an acid radical comprising condensing said quaternary salt with a heterocyclic ammonium quaternary salt having a reactive constituent selected from the group consisting of aryl aminovinyl groups, aryl aminobutadienyl groups, halogen atoms and thioether groups in a position selected from the alpha and gamma positions, in the presence of an alkaline condensing agent.

14. A process for preparing merocarbocyanine dyes containing the 4,5-dihydro-beta-naphthothiazole nucleus and having the general formula wherein R represents a member selected from the group consisting of alkyl, aralkyl and aryl groups, R represents a member selected from the group consisting of alkyl and aryl groups, L is a methine group, n is a positive integer of from 1 to 4 and Q is a member selected from the group consisting of oxygen, sulfur, selenium and =NR' comprising condensing in an alkaline medium a quaternary salt having the general formula C-CH| \g/ IX" R wherein R represents a member selected from the group consisting of alkyl and aralkyl groups and X- represents an acid radical with a ketomethylene heterocyclic compound having a reactive arylaminoet ykn group ll the 5 position. i i

15. A process for preparing pyrrolocarbocyanine dyes containing the 4,5-dihydro-beta-naphthothiazole nucleus and having the formula wherein R represents a member selected from the group consisting of alkyl, aralkyl and aryl groups and X- represents an anion comprising condensing a quaternary salt having the formula c H C l X R wherein R represents a member selected from the group consisting of alkyl and aralkyl groups and X'- represents an acid radical with an agent selected from the group consisting of l-alkyl and l-aryl-2,5-dimethyl-3-pyrrole carboxaldehyde in the presence of an alkaline condensing agent.

16. A process for preparing styryl dyes containing the 4,5-dihydro-beta-naphthothiazole nucleus and having the formula C-CH:

C-CE

2,166,736 White et al. July 18, 1939 2,263,749 White et al Nov. 25, 1941 2,320,654 Riester June 1, 1943 2,322,015 Hamer et a1 June 15, 1943 2,330,203 Brooker et al. Sept. 28, 1943 2,338,782 Riester Jan. 11, 1944 2,340,882 Kendall Feb. 8, 1944 2,353,164 Kendall et al July 11, 1944 2,495,260 Jenner et al. Jan. 24, 1950 OTHER REFERENCES Chemical Abstracts 16:3101 (Copy in S.L.) (Abstract of Brit. Med. Journal, 1922, I, 51455).

Chemical Abstracts 19:530 (Copy in S.L.) (Abstract of Proc. Roy. Soc., London, 96B, 317-333, 1924).

Clerc: Photography Theory and Practice, 3rd ed., page 151, Pitman Pub. Corp., N.Y., 1942. (Copy in Div. 60.) 

4. A DYE SELECTED FROM THE GROUP CHARACTERIZED BY THE FOLLOWING GEMERAL FORMULA: 